1. Field of the Invention
The present invention relates to a method for manufacturing a semiconductor. More particularly, the present invention relates to a method for manufacturing a metal structure by filling a trench formed in a substrate with a metal material.
2. Description of the Prior Art
As semiconductor fabrication technology advances, it is possible to manufacture semiconductor devices having higher aspect ratios, i.e., higher ratios of width to depth of trenches. Also, in a conventional method, a trench having a higher aspect ratio is filled with a metal material to be used for interlayer electrical connections in multi-layered structures, or to form a third structure with other structures.
FIGS. 1A to 1C illustrate schematic cross-sectional views showing an example of a prior art method for manufacturing a metal structure by means of a trench. In the method for manufacturing the metal structure using the trench, first, as shown in FIG. 1A, a semiconductor substrate 10 is etched to a desired shape and depth by means of a patterning process, thereby forming a trench 15. Then, a seed layer 12 is deposited over the semiconductor substrate 10 having the trench 15. Then, a plating process is performed on the semiconductor substrate 10 deposited with the seed layer 12, as shown in FIG. 1B. Subsequently, the seed layer 12 and a metal material 14 on the semiconductor substrate 10 are physically or chemically etched, as shown in FIG. 1C. As such, since the metal structure is present in the semiconductor substrate 10, it is possible to easily manufacture a multi-layered structure.
However, a problem may arise in a case that the structure is formed by filling the trench 15 with the metal material 14. Because the entire surface of the semiconductor substrate 10 that is deposited with the seed layer 12 is subjected to plating during a plating process, the inlet of the trench may become clogged before the trench 15, which has a higher aspect ratio, can be completely filled with the metal material 14. In this case, an undesirable void 16 is generated, causing reliability of the fabricated device to be degraded.
FIGS. 2A to 2C illustrate schematic views showing an example of another prior art method for manufacturing a metal structure by means of a trench. In this method for manufacturing the metal structure, first, a seed layer 22 is deposited over a semiconductor substrate 20, as shown in FIG. 2A, and a mold 23 is formed over the deposited seed layer 22 to form a trench 25. Then, the trench 25 formed by the mold 23 is filled with a metal material 24, as shown in FIG. 2B. Thereafter, the mold 23 and the seed layer 22 underlying the mold 23 are removed, as shown in FIG. 2C.
As such, the method for manufacturing the metal structure on the semiconductor substrate 20 by means of the mold 23 is very easy. However, in a case where the metal structure is formed on the semiconductor substrate 20 by means of the mold 23, there is a problem that subsequent processes become very difficult when manufacturing a multi-layered structure. Particularly, in a case in which a planar structure is formed on a plated structure, a plurality of processes must be added, thereby increasing complexity and cost of the manufacturing process.